Pneumatic Actuator

Abstract

A first piston (114) of a first cylinder (110) and a second piston (134) of a second cylinder (130) are connected so as to achieve the same amount of displacement. One pressure-receiving area of the first piston (114) is the smallest, and the pressure-receiving area of the second piston (134) which is on the same side is the third-smallest. When the two air chambers of the first cylinder (110) and the two air chambers of the second cylinder are referred to respectively as the first air chamber, second air chamber, third air chamber, and fourth air chamber in order from the chamber having the smallest pressure-receiving area to the chamber having the largest pressure-receiving area, in an advancing stroke a control valve (150) connects an air pressure source (102) to the first air chamber, connects the second air chamber and the third air chamber, and opens the fourth air chamber to the atmosphere (104).

Description

[Technical field]

[0001] The present disclosure relates to pneumatic actuators. [Background technology]

[0002] Compared to other actuators, pneumatic actuators have the advantages of being simple in structure, inexpensive, and lightweight. Pneumatic actuators can easily generate large forces. Furthermore, the air used by pneumatic systems is inexhaustible and clean. For these reasons, pneumatic systems using pneumatic actuators are used in assembly equipment and conveying equipment in various factories for automobiles, semiconductors, food, and the like. Furthermore, pneumatic actuators, unlike electric actuators, do not generate magnetic fields or electric fields, making them suitable for applications where magnetic fields and electric fields must be avoided.

[0003] On the other hand, pneumatic actuators have the disadvantage of low energy efficiency because the compressed air must be released directly into the atmosphere. Due to this disadvantage, there has been a recent trend to replace pneumatic actuators with electric actuators. Summary of the Invention [Problem to be solved by the invention]

[0004] It is in this context that the present disclosure has been made, and it is an exemplary object of one aspect thereof to provide a pneumatic actuator with improved efficiency. [Means for solving the problem]

[0005] An embodiment of the present disclosure relates to a pneumatic cylinder. The pneumatic cylinder includes a first cylinder, a second cylinder, and a control valve. The first cylinder includes a first cylinder tube and a first piston that divides the space in the first cylinder tube into two air chambers. The second cylinder includes a second cylinder tube and a second piston that divides the space in the second cylinder tube into two air chambers and is connected to the first piston so that the displacement amount is the same, that is, so that the displacements are linked. Of the two pressure receiving surfaces of the first piston and the two pressure receiving surfaces of the second piston, one pressure receiving area of ​​the first piston is the smallest, and one pressure receiving area of ​​the second piston is the third smallest. When the two air chambers of the first cylinder and the two air chambers of the second cylinder are called the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber, in order from the one with the smallest pressure-receiving area to the largest, the control valve connects the air pressure source to the first air chamber, connects the second air chamber and the third air chamber, and opens the fourth air chamber to the atmosphere on the forward stroke.

[0006] An embodiment of the present disclosure also relates to a pneumatic cylinder. The pneumatic cylinder includes a plurality of N (N≧2) cylinders and a control valve. Each of the N cylinders includes a cylinder tube and a piston that divides the space in the cylinder tube into two air chambers. The pistons of the N cylinders are connected so that the displacement amounts are equal, that is, so that the displacements are linked. Among all the pressure receiving surfaces of the pistons of the N cylinders, the pressure receiving area of ​​one of the i-th (1≦i≦N) pistons is the (2i-1)th smallest. When the two air chambers of each of the N cylinders are referred to as the first air chamber, the second air chamber, ..., the (2N-1)th air chamber, and the (2N)th air chamber in order from the smallest to the largest pressure receiving area, the control valve connects an air pressure source to the first air chamber in the (i) forward stroke, opens the (2N) air chamber to the atmosphere, and connects the other pairs of adjacent two air chambers. Effect of the Invention

[0007] According to certain aspects of the present disclosure, the efficiency of pneumatic actuators can be improved. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating the energy required to compress air. [Diagram 2] 2(a) and (b) are diagrams illustrating the operation of the pneumatic cylinder. [Diagram 3] 3(a) and (b) are diagrams illustrating a differential circuit in a hydraulic system. [Figure 4] 4(a) and (b) are diagrams illustrating a differential circuit in a pneumatic system. [Diagram 5] 1A and 1B are diagrams illustrating a double cylinder actuator according to an embodiment. [Figure 6] FIG. 2 is a diagram illustrating the forward stroke of a double-acting double-cylinder actuator. [Figure 7] FIG. 2 is a diagram illustrating the return stroke of a double-acting double-cylinder actuator. [Figure 8] FIG. 2 is a diagram illustrating the return stroke of a single-acting double-cylinder actuator. [Figure 9] FIG. 1 is a diagram illustrating the output characteristics of the forward stroke of a double-acting double-cylinder actuator. [Figure 10] FIG. 1 is a diagram illustrating the output characteristics of the return stroke of a double-acting double-cylinder actuator. [Figure 11] FIG. 1 is a diagram illustrating the output characteristics of a forward stroke of a single-acting double-cylinder actuator. [Figure 12] FIG. 1 is a diagram illustrating the output characteristics of a return stroke of a single-acting double-cylinder actuator. [Figure 13] FIG. 11 is a diagram showing the relationship between the output magnification of a double-acting double-cylinder actuator and α. [Figure 14] FIG. 11 is a diagram showing the relationship between the output magnification of a single-acting double-cylinder actuator and α. [Figure 15] FIG. 1 illustrates a dual cylinder actuator with smoothed output. [Figure 16] 16(a) to 16(c) are diagrams showing a basic type, a first modified example, and a second modified example of a double cylinder actuator. [Figure 17] 17(a) and 17(b) are diagrams showing modified examples 3 and 4 of the double cylinder actuator. [Figure 18] 18(a) and (b) are diagrams showing double cylinder actuators according to modified examples 5 and 6. FIG. [Figure 19] 19(a) and (b) are diagrams showing double cylinder actuators according to modified examples 7 and 8. In FIG. [Figure 20] 20(a) and (b) are diagrams showing a double-cylinder actuator using a single-rod cylinder. [Figure 21] FIG. 21 is a diagram showing a double cylinder actuator 100a according to the ninth modification. [Figure 22] FIG. 23 is a diagram showing a double cylinder actuator according to a tenth modification. [Figure 23] FIG. 23 is a diagram showing a double cylinder actuator according to an eleventh modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Overview of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a basic understanding of some concepts of one or more embodiments as a prelude to the detailed description that follows, and is not intended to limit the scope of the invention or disclosure. Additionally, this summary is not intended to be a comprehensive overview of all possible embodiments, nor is it intended to limit essential elements of the embodiments. For convenience, the term "one embodiment" may be used to refer to one embodiment or multiple embodiments disclosed herein.

[0010] A pneumatic cylinder according to one embodiment includes a first cylinder, a second cylinder, and a control valve. The first cylinder includes a first cylinder tube and a first piston that divides the space in the first cylinder tube into two air chambers. The second cylinder includes a second cylinder tube and a second piston that divides the space in the second cylinder tube into two air chambers and is connected to the first piston so that the displacement amount is the same as that of the first piston. Of the two pressure receiving surfaces of the first piston and the two pressure receiving surfaces of the second piston, one of the pressure receiving areas of the first piston is the smallest, and one of the pressure receiving areas of the second piston is the third smallest. When the two air chambers of the first cylinder and the two air chambers of the second cylinder are referred to as the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in order from the smallest to the largest, the control valve (i) connects an air pressure source to the first air chamber, connects the second air chamber and the third air chamber, and opens the fourth air chamber to the atmosphere during the forward stroke.

[0011] In this configuration, the second and third air chambers act as a differential circuit. Therefore, if there is compressed air remaining in the second and third air chambers just before the forward stroke, it is expanded and used to drive the piston, making it possible to effectively use the energy of the compressed air and increasing the efficiency of the pneumatic cylinder. In addition, the combined force of the outputs of the two cylinders at this time is greater than that of a single cylinder.

[0012] In one embodiment, the control valve may (ii) connect the first and second air chambers to the air pressure source and connect the third and fourth air chambers to the air pressure source during the return stroke. In this embodiment, the pneumatic cylinder functions as a double-acting cylinder. During the return stroke, the pair of the first and second air chambers and the pair of the third and fourth air chambers act as a differential circuit, and it is possible to obtain an output in the return direction while effectively utilizing the energy of the remaining compressed air. In addition, the combined force of the outputs of the two cylinders at this time is greater than that of a single cylinder.

[0013] In one embodiment, the control valve may (iii) connect the first air chamber and the second air chamber in a state where they are disconnected from the air pressure source, and connect the third air chamber and the fourth air chamber during the return stroke. In this embodiment, the pneumatic cylinder functions as a single-acting cylinder that does not consume compressed air during the return stroke. During the return stroke, the pair of the first air chamber and the second air chamber and the pair of the third air chamber and the fourth air chamber act as a differential circuit, and it is possible to obtain an output in the return direction while effectively utilizing the energy of the remaining compressed air.

[0014] In one embodiment, the first and second cylinders may be arranged non-coaxially, which allows the axial dimension of the pneumatic cylinder to be reduced.

[0015] In one embodiment, the first air chamber and the second air chamber may be formed in the same cylinder, and the third air chamber and the fourth air chamber may be formed in the same cylinder.

[0016] In one embodiment, the first and second cylinders can be single rod cylinders, which can reduce costs.

[0017] In one embodiment, the first cylinder and the second cylinder may be arranged coaxially.

[0018] In one embodiment, a first air chamber, a second air chamber, a third air chamber, and a fourth air chamber may be arranged in this order in the axial direction.

[0019] In one embodiment, the third air chamber, the fourth air chamber, the first air chamber, and the second air chamber may be arranged in this order in the axial direction.

[0020] In one embodiment, the first air chamber, the fourth air chamber, the third air chamber, and the second air chamber may be arranged in this order in the axial direction.

[0021] In one embodiment, the third air chamber, the second air chamber, the first air chamber, and the fourth air chamber may be arranged in this order in the axial direction.

[0022] In one embodiment, the control valve may include a first control valve and a second control valve having four ports. The first control valve and the second control valve are configured such that (a) in a first position, the first port communicates with the second port, and the third and fourth ports are closed, and (b) in a second position, the first and second ports are closed, and the fourth port communicates with the third port. The first and third ports of the first control valve are connected to the second air chamber, the second port of the first control valve is connected to the third air chamber and the fourth port of the second control valve, the fourth port of the first control valve is connected to the first air chamber and the air pressure source, the first and third ports of the second control valve are connected to the fourth air chamber, and the second port of the second control valve is connected to the atmosphere. In the case of a double-acting cylinder, the first and second control valves can be configured using commercially available products (a four-port directional control valve or two two-port directional control valves).

[0023] (Embodiment) Hereinafter, the present disclosure will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and duplicated descriptions will be omitted as appropriate. In addition, the embodiments are not intended to limit the disclosure, but are merely examples, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure.

[0024] In addition, the dimensions (thickness, length, width, etc.) of each component shown in the drawings may be enlarged or reduced as appropriate for ease of understanding. Furthermore, the dimensions of multiple components do not necessarily represent their relative sizes, and even if a component A is drawn thicker than another component B on the drawings, component A may actually be thinner than component B.

[0025] 1. Efficiency of Traditional Pneumatic Actuators First, the efficiency of conventional pneumatic actuators is considered.

[0026] The compressed air used in pneumatic systems is usually 0.7MPa (gauge) [=0.8MPa (abs)], which is created by compressing air at atmospheric pressure (0.1MPa (abs)) using a compressor.

[0027] Figure 1 is a diagram explaining the energy required to compress air. The energy dE required to compress air with pressure P and volume V by dV is expressed by formula (1).

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[0028] On the other hand, the change in the state of air is expressed by equation (2), where T is the temperature and R is the gas constant.

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[0029] The actual change in state is not an isothermal change, but an adiabatic or polytropic change, but for ease of understanding and to simplify the explanation, we will assume an isothermal change. If we look at the event over a relatively long time scale, the final air temperature will converge to the ambient temperature, so this assumption is useful for obtaining approximate values. If we assume an isothermal change, dPV+pdV=dT=0, so equation (1) becomes equation (3). By integrating this, we obtain equation (4).

number

number

[0030] Therefore, the atmospheric pressure P a = 0.1 [MPa (abs)] of air is compressed to pressure P S = 0.8 [MPa (abs)], the energy E0 required to compress the air to volume V is expressed by equation (5) if the state change is considered to be an isothermal change.

number

[0031] Next, the efficiency of a pneumatic actuator will be described using a pneumatic cylinder as an example. 2(a) and (b) are diagrams explaining the operation of the pneumatic cylinder 10. Fig. 2(a) shows the forward stroke, and Fig. 2(b) shows the return stroke. The internal space of the pneumatic cylinder 10 is divided into a left chamber 14 and a right chamber 16 by the piston 12.

[0032] As shown in FIG. 2(a), in the forward stroke, compressed air is supplied to the left chamber 14, and the right chamber 16 is open to the atmosphere. Then, when the piston 12 reaches the right end, the supply of compressed air is stopped. At this time, the air pressure in the left chamber 14 is P S It is.

[0033] Next, in the return stroke shown in FIG. 2(b), the left chamber 14 is opened to the atmosphere, and the pressure P S The compressed air is discharged to the outside. Otherwise, the return stroke will not work properly. In this case, the energy (work) E obtained by the air pressure during the forward stroke is expressed by the formula (6), where V is the volume of the left chamber 14.

number

[0034] Therefore, in the normal usage, where the compressed air is discarded on the return stroke, the energy efficiency η can be obtained from equations (5) and (6) as shown in equation (7).

number

[0035] In other words, a simple calculation would result in a maximum efficiency of about 0.5. The reason for this low efficiency is that the high-pressure air in the left chamber 14 is simply discharged to the outside during the return stroke.

[0036] 2. Differential Circuit In the pneumatic cylinder according to the embodiment described below, the high-pressure air is not discarded as it is, but the expansion process of the high-pressure air is also used to drive the cylinder, thereby greatly increasing energy efficiency. However, as the air expands, the pressure decreases and it cannot be used as a sufficient driving force. Therefore, some kind of ingenuity is required to use the air in the expansion process for driving.

[0037] 2.1 Differential circuits in hydraulic systems In order to understand the pneumatic cylinder according to the embodiment, it is essential to understand the differential circuit which is often used in hydraulic circuits. Therefore, in this section, the differential circuit will be described.

[0038] 3(a) and (b) are diagrams explaining a differential circuit 20 in a hydraulic system. The differential circuit 20 includes a hydraulic cylinder 30, a pump 22, a control valve 24, and a tank 26. The hydraulic cylinder 30 has a configuration similar to that of the pneumatic cylinder 10 in FIG. 2, and the internal space of the cylinder is divided into a left oil chamber 34 and a right oil chamber 36 by a piston 32.

[0039] During the forward stroke in FIG. 3( a ), oil from the pump 22 flows into the left oil chamber 34 of the cylinder, and oil leaving the right oil chamber 36 returns to the tank 26 .

[0040] On the other hand, during the return stroke in FIG. 3(b), the oil chambers 34, 36 on both sides of the cylinder are pressurized with the same pressure. Here, the pressure-receiving area A1 of the left oil chamber 34 of the piston 32 is different from the pressure-receiving area A2 of the right oil chamber 36. In this example, the pressure-receiving area A1 of the left oil chamber 34 is larger than the pressure-receiving area A2 of the right oil chamber 36, because the cross-sectional area A of the piston rod 38 is larger than the cross-sectional area A of the right oil chamber 36. R It has become smaller by just a fraction.

[0041] In other words, because the pressure-receiving area of ​​the right oil chamber 36 is large, the leftward force becomes greater, and the piston rod 38 moves leftward. At this time, the oil coming out of the left oil chamber 34 and the oil from the pump 22 combine and flow into the right oil chamber 36, causing the cylinder to move at high speed. In this way, a feature of the differential circuit 20 is that it can move at high speed on the return stroke, and the smaller the area difference |A2-A1| on both sides of the cylinder is, the faster it moves. If the cylinder speed is v, the following equation holds:

number

[0042] Therefore, the cylinder speed v is expressed by equation (9). Since the oil from the pump 22 is used only to fill the volume of the piston rod 38, the thinner the rod is, the faster the cylinder speed v becomes.

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[0043] On the other hand, the output is as shown in equation (10), and the thinner the piston rod 38 is, the smaller the output (A R The smaller the output, the smaller the

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[0044] To take advantage of these characteristics, the differential circuit 20 has been used in the return stroke when a fast return is desired and a large output is not required.

[0045] 2.2 Application of differential circuits to pneumatic systems Next, application of the differential circuit to a pneumatic system will be described. Figures 4(a) and (b) are diagrams illustrating a differential circuit 40 in a pneumatic system. The differential circuit 40 includes the pneumatic cylinder 10, an air pressure source (compressor) 42, and a control valve 44.

[0046] Figure 4(a) shows the forward stroke, and its operation is the same as that of the differential circuit 20 in the hydraulic system.

[0047] Figure 4(b) shows the return stroke. When the inventor applied the differential circuit used in the hydraulic system to the pneumatic system, the inventor focused on a major feature not seen in the hydraulic system during the return stroke.

[0048] Specifically, when the differential circuit 40 is used in the pneumatic system, as shown in Figure 4(b), during the return stroke, it can move without necessarily supplying air from the pneumatic source 42. This is because air expands, unlike oil. In Figure 4(b), since the passage connecting the left chamber 14 and the right chamber 16 of the cylinder opens, the left chamber 14 and the right chamber 16 have the same pressure, but there is an area difference (A1 < A2), so the piston 12 moves to the left (return stroke).

[0049] Let the cylinder length be L and the length of the right chamber 16 of the piston 12 be x. The volume V of the air chamber in the cylinder is expressed by the following formula, and as the piston 12 moves to the left, that is, as the length x increases, the volume V increases. V = A1×(L - x) + A2×x =(A2 - A1)×x + A1×L

[0050] Assuming an isothermal change as the state change, since PV = constant, when the volume V increases as the piston 12 moves, the pressure P gradually decreases. If the pneumatic source 42 is connected as shown by the dashed line in the figure, compressed air is supplied from there, so the pressure P does not decrease even if the piston 12 moves.

[0051] The above is the behavior of the differential circuit in the pneumatic system.

[0052] 3. Pneumatic Actuator According to the Embodiment Hereinafter, the pneumatic actuator according to the embodiment will be described in detail. This pneumatic cylinder uses the concept of the differential circuit described above in three stages, and improves the efficiency by effectively using all (or most of) the output during the expansion of the compressed air from the supply pressure to the atmospheric pressure.

[0053] 3.1 Basic Configuration The pneumatic actuator according to this embodiment is formed by directly connecting two pneumatic cylinders with different pressure receiving areas on both sides of the piston, and is hereinafter also referred to as a double-cylinder actuator. There are four pressure receiving surfaces of the double-cylinder actuator 100, and the pressure receiving areas are A1 and A2 on both sides of the first cylinder, and A3 and A4 on both sides of the second cylinder. These areas are arranged in ascending order as A1 < A2 < A3 < A4.

[0054] FIG. 5 is a diagram showing the double-cylinder actuator 100 according to the embodiment. The double-cylinder actuator 100 includes a first cylinder 110, a second cylinder 130, and a control valve 150. The control valve 150 can use a solenoid valve, but is not limited thereto. In the figure, the right direction is the direction of the output in the forward stroke of the double-cylinder actuator 100, and the left direction is the direction of the output in the return stroke of the double-cylinder actuator 100. Note that the double-cylinder actuator 100 is assumed to reciprocate repeatedly many times.

[0055] The first cylinder 110 includes a first cylinder tube 112 and a first piston 114. The first piston 114 is displaceable within the first cylinder tube 112, and the space within the first cylinder tube 112 is partitioned by the first piston 114 into a left air chamber 116 and a right air chamber 118.

[0056] The pressure receiving area A1 of the first surface (the left air chamber 116 side) of the first piston 114 is smaller than the pressure receiving area A2 of the second surface (the right air chamber 118 side). A1 < A2

[0057] In this embodiment, the first cylinder 110 is a double-rod cylinder, and a left rod 120 is provided on the left air chamber 116 side of the first piston 114, and a right rod 122 is provided on the right air chamber 118 side. C1 , the cross-sectional area of ​​the left rod 120 is A R1_L , the cross-sectional area of ​​the right rod 122 is A R1_R Then, the following relation holds: A1=A C1 -A R1_L A2=A C1 -A R1_R However, A R1_L >A R1_R

[0058] The second cylinder 130 includes a second cylinder tube 132 and a second piston 134. The second piston 134 is displaceable within the second cylinder tube 132, and the space within the second cylinder tube 132 is divided by the second piston 134 into a left air chamber 136 and a right air chamber 138.

[0059] The first cylinder 110 and the second cylinder 130 are arranged so that the first piston 114 and the second piston 134 are parallel to each other. The second piston 134 is connected to the first piston 114 so that the second piston 134 has the same displacement as the first piston 114. In FIG. 5, the second piston 134 and the first piston 114 are connected to each other via the right rod 122 and the left rod 140.

[0060] A pressure receiving area A3 of a first surface (left air chamber 136 side) of the second piston 134 is smaller than a pressure receiving area A4 of a second surface (right air chamber 138 side). A3 <A4

[0061] In this embodiment, the second cylinder 130 is also a double-rod cylinder, and a left rod 140 is provided on the left air chamber 136 side of the second piston 134, and a right rod 142 is provided on the right air chamber 138 side. C2 , the cross-sectional area of ​​the left rod 140 is A R2_L, when the cross-sectional area of the right rod 142 is A R2_R , the following relational expressions hold. A3 = A C2 -A R2_L A4 = A C2 -A R2_R However, A R2_L >A R2_R

[0062] Furthermore, in this embodiment, the relationship A2 < A3 holds. That is, A1 < A2 < A3 < A4 such a relationship holds. The two air chambers 116, 118 of the first cylinder 110 and the two air chambers 136, 138 of the second cylinder 130 are, in order from the one with the smallest pressure-receiving area to the largest, referred to as the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber, and new reference numerals 161, 162, 163, 164 are attached. In this example, the correspondence is as follows. First air chamber 161 = left air chamber 116 of the first cylinder 110 Second air chamber 162 = right air chamber 118 of the first cylinder 110 Third air chamber 163 = left air chamber 136 of the second cylinder 130 Fourth air chamber 164 = right air chamber 138 of the second cylinder 130

[0063] A part or all of the rods of the first cylinder 110 and the second cylinder 130 are used as design parameters for the pressure-receiving area and also serve as coupling means for connecting the first piston 114 and the second piston 134.

[0064] In this example, the control valve 150 is shown as a 6-port 2-position valve. The first port (1) to the sixth port (6) are connected to the air pressure source 102, the atmosphere 104, and the first air chamber 161 to the fourth air chamber 164, respectively. Note that the control valve 150 is only required to be able to switch at least between the first and second positions described below, and the number of positions is not limited to two. For example, when it is assumed that the valve will be stopped at a mid-stroke position, a directional control valve having a closed center function may be used, and in this case, a 3-position valve may be employed. In addition, the method of holding and operating the control valve is not particularly limited, and a single solenoid type (spring return type), double solenoid type, or other type of valve may be used.

[0065] Generally, pneumatic cylinders are classified into "double-acting cylinders" that output during both the forward and return strokes, and "single-acting cylinders" that output during the forward stroke but do not require output during the return stroke and return using a spring or their own weight. Therefore, the double-cylinder actuator 100 according to the embodiment may also be a double-acting cylinder or a single-acting cylinder. The configuration of the control valve 150 differs depending on whether the double-cylinder actuator 100 is a single-acting cylinder or a double-acting cylinder. Therefore, the following description will be given in the order of double-acting cylinders and single-acting cylinders.

[0066] (1) Double-acting cylinder (1-1) Itinerary 6 is a diagram illustrating the forward stroke of the double-acting double-cylinder actuator 100a. During the forward stroke, the control valve 150a connects the first air chamber 161 to the air pressure source 102, connects the second air chamber 162 to the third air chamber 163, and opens the fourth air chamber 164 to the atmosphere 104. Specifically, the control valve 150a is set to the first position, and communication is established from the first port (1) to the third port (3), communication is established between the fourth port (4) and the fifth port (5), and communication is established from the sixth port (6) to the second port (2).

[0067] During the forward stroke (the movement of the rightward output), compressed air is supplied to the first air chamber 161 to obtain a rightward output. Also, the second air chamber 162 and the third air chamber 163 are connected. Since A2 < A3, a rightward output can be obtained based on the same principle as a differential circuit. The resultant force F of these two rightward outputs is greater than that in the case of only a single cylinder 110.

[0068] (1-2) Return stroke Figure 7 is a diagram for explaining the return stroke of the double-acting double-cylinder actuator 100a. In the return stroke, the control valve 150a connects the first air chamber 161 and the second air chamber 162 to the pneumatic source 102, and connects the third air chamber 163 and the fourth air chamber 164. Specifically, the control valve 150a is set to the second position, the first port (1) and the third port (3) are conducting toward the fourth port (4), the connection between the fifth port (5) and the sixth port (6) is conducting, and the second port (2) is in a closed state (closed).

[0069] During the return stroke (the movement of the leftward output), compressed air is supplied to the second air chamber 162. At the same time, the second air chamber 162 and the first air chamber 161 of the first cylinder 110 are connected. Since A1 < A2, a leftward output can be obtained based on the same principle as a differential circuit.

[0070] Also, the third air chamber 163 and the fourth air chamber 164 of the second cylinder 130 are connected. Since A3 < A4, a leftward output can also be obtained based on the same principle as a differential circuit. The resultant force F of these two leftward outputs R is greater than that in the case of only a single cylinder 110.

[0071] Thus, in a double-acting cylinder, during both the forward stroke and the return stroke, the outputs F, F R are greater than those in the case of only a single cylinder 110. This is because the force during the expansion process of the compressed air is also utilized.

[0072] For example, if the pressure-receiving area ratio of the double cylinder actuator 100 is A1:A2:A3:A4=1:2:4:8, the compressed air supply pressure is normally 0.8 [MPa (abs)], and if the state change is considered to be an isothermal change, the pressure of each chamber is inversely proportional to the volume, so the pressure of each air chamber changes approximately as follows in the forward stroke and return stroke. (Forward stroke) First air chamber 161 = 0.8 MPa Second air chamber 162 = 0.8 → 0.8 × (2 / 4) = 0.4 MPa Third air chamber 163 = 0.8 → 0.8 × (2 / 4) = 0.4 MPa 4th air chamber 164 = 0.1MPa (atmospheric pressure) (Return process) First air chamber 161 = 0.8 MPa Second air chamber 162 = 0.8 MPa Third air chamber 163 = 0.4 → 0.4 × (4 / 8) = 0.2 MPa The fourth air chamber 164 = 0.4 → 0.4 × (4 / 8) = 0.2 MPa

[0073] In the last, fourth air chamber 164, the pressure drops to about 0.2 MPa, and it can be seen that the force of the expansion process of the compressed air can be fully utilized to a pressure closer to atmospheric pressure than in conventional actuators. Furthermore, for example, if the output of the double cylinder actuator 100 is twice that of a single cylinder 110, the total pressure-receiving area of ​​the double cylinder actuator 100 can be half that of the conventional actuator to obtain the same output. As a result, the amount of air consumed is halved, and efficiency approaches 100% from the current approximately 50%.

[0074] When only a single cylinder is used, noise is generated when the compressed air is discharged into the atmosphere. In order to reduce this noise, a silencer is often inserted. When using the double cylinder actuator 100, the air is discharged when its pressure has dropped to near atmospheric pressure, so the silencer can be omitted, which can reduce costs.

[0075] (2) Single-acting cylinder (2-1) Itinerary The forward stroke in the single-acting cylinder is the same as the forward stroke in the double-acting cylinder and has been explained with reference to FIG. 6, so the explanation will be omitted.

[0076] (2-2) Return stroke 8 is a diagram illustrating the return stroke of the single-acting double-cylinder actuator 100b. In the single-acting double-cylinder actuator 100b, the function of the control valve 150b in the return stroke is different from that of the double-acting control valve 150a. In the return stroke, the control valve 150b connects the first air chamber 161 and the second air chamber 162 in a state in which they are separated from the air pressure source 102, and connects the third air chamber 163 and the fourth air chamber 164. Specifically, the control valve 150b is set to the second position, the first port (1) and the second port (2) are in a closed state, the third port (3) and the fourth port (4) are connected, and the fifth port (5) and the sixth port (6) are connected.

[0077] In a single-acting cylinder, output is not necessarily required during the return stroke (leftward output movement), so compressed air from the air pressure source 102 is not supplied to the second air chamber 162. Therefore, compressed air is not consumed during the return stroke. However, since the pair of the first air chamber 161 and the second air chamber 162, and the pair of the third air chamber 163 and the fourth air chamber 164 each form a differential circuit, a certain amount of output can be obtained even during the return stroke.

[0078] In a single-acting cylinder, when the pressure-receiving area ratio of the double-cylinder actuator 100 is A1:A2:A3:A4=1:2:4:8 and the compressed air supply pressure is 0.8 [MPa (abs)], the pressure in each air chamber transitions approximately as follows during the forward stroke and the return stroke. (Going process) First air chamber 161 = 0.8 MPa Second air chamber 162 = 0.4 → 0.4 × (2 / 4) = 0.2 MPa Third air chamber 163 = 0.4 → 0.4 × (2 / 4) = 0.2 MPa 4th air chamber 164 = 0.1MPa (atmospheric pressure) (Return process) First air chamber 161 = 0.8 → 0.8 × (1 / 2) = 0.4 MPa Second air chamber 162 = 0.8 → 0.8 × (1 / 2) = 0.4 MPa Third air chamber 163 = 0.2 → 0.2 × (4 / 8) = 0.1 MPa 4th air chamber 164 = 0.2 → 0.2 × (4 / 8) = 0.1 MPa (atmospheric pressure)

[0079] In the last, fourth air chamber 164, the pressure drops to atmospheric pressure of 0.1 MPa, which shows that energy can be utilized more efficiently than in the double-acting cylinder.

[0080] 4. Output characteristics of the double cylinder actuator 100 Next, the output characteristics of the double cylinder actuator 100 will be described for both the double-acting cylinder and the single-acting cylinder. (1) Double-acting cylinder (1-1)Output during outbound travel 9 is a diagram illustrating the output characteristics of the forward stroke of the double-acting double-cylinder actuator 100a. The length of the first cylinder 110 and the second cylinder 130 is L, and the position of the first piston 114 and the second piston 134 is x. In the forward stroke, x=L is the initial state, and x=0 is the final state. In the figure, t indicates the thickness of the piston.

[0081] The pressures of the first air chamber 161, the second air chamber 162, the third air chamber 163, and the fourth air chamber 164 are denoted as P1, P2, P3, and P4, respectively.

[0082] In FIG. 9, if the rightward output is F, then P2=P3, and therefore equation (11) holds.

number

[0083] At the initial state x=L, the final state of the previous return stroke, P2=P S However, as x changes to 0, P2=P3=PS Therefore, P2 = P3 = (A2 / A3)P S Also, P1=P S ,P4=P a Since the pressure remains constant (atmospheric pressure), the output of the initial state is expressed by equation (12) and the output of the final state is expressed by equation (13).

number

number

[0084] (1-2) Output during the return stroke 10 is a diagram illustrating the output characteristics of the double-acting double-cylinder actuator 100a during the return stroke. During the return stroke, x=0 is the initial state, and x=L is the final state.

[0085] In Fig. 10, the leftward output is F R Then, since P1=P2, P3=P4, equation (14) holds.

number

[0086] In this case, the pair of the first air chamber 161 and the second air chamber 162, and the pair of the third air chamber 163 and the fourth air chamber 164 are connected to each other, and further, the second air chamber 162 is supplied with compressed air from the air pressure source 102, which is a pressure source. In the initial state x=0, P3=(A2 / A3)P, which is the final state of the immediately preceding forward stroke, S However, as x changes to L, P3 = (A2 / A3)P S Therefore, P3 = P4 = (A2 / A3)P S ×(A3 / A4)=(A2 / A4)P S The first air chamber 161 and the second air chamber 162 change toward P1=P2=P S Therefore, the output of the initial state is expressed by equation (15), and the output of the final state is expressed by equation (16).

number

number

[0087] As an example, in the case of A2 / A1=A3 / A2=A4 / A3=2, F and F of a double-acting cylinder R This is the case where A4 = 2A3 = 4A2 = 8A1. The compressed air supply pressure is P S = 0.8MPa (abs). That is, P S =8P a It is.

[0088] The output F of the initial and final states during the outward stroke is as follows:

number

number

[0089] If the drop in the output in the final state is a problem, it is necessary to smooth the outputs in the initial and final states. This method will be described later.

[0090] (2) Single-acting cylinder What will be explained here is the output of the single-acting double cylinder actuator 100b. A single-acting cylinder outputs power during the forward stroke, but does not need to output power during the return stroke, and returns using a spring or its own weight.

[0091] (2-1)Output during outbound travel 11 is a diagram illustrating the output characteristics of the single-acting double-cylinder actuator 100b in the forward stroke. In the forward stroke, x=L is the initial state, and x=0 is the final state.

[0092] In FIG. 11, if the rightward output is F, then since P2=P3, the following equation holds.

number

[0093] In this case, at the initial state x=L, the final state of the previous return stroke, P2=(A1 / A2)P S However, as x changes to 0, P2 = P3 = (A1 / A2)P S Therefore, P2=P3=(A1 / A2)P S ×(A2 / A3)=(A1 / A3)P S Also, P1=P S ,P4=P a Since the pressure remains constant (atmospheric pressure), the output F in the initial state and the final state are expressed by equations (17) and (18), respectively.

number

number

[0094] (2-2) Output during the return stroke 12 is a diagram illustrating the output characteristics of the single-acting double-cylinder actuator 100b during the return stroke. In the return stroke, x=0 is the initial state, and x=L is the final state.

[0095] In Figure 12, the leftward output is F R Then, P1=P2, P3=P4, so equation (14) holds.

number

[0096] In this case, the pair of the first air chamber 161 and the second air chamber 162, and the pair of the third air chamber 163 and the fourth air chamber 164 are connected. In the initial state x=0, the final state of the immediately preceding forward stroke, P3=P4=(A1 / A3)P S And P1=P2=P S As x changes to L, P1=P2=P S So P1 = P2 = (A1 / A2)P S P3=P4=(A1 / A3)P S Therefore, P3 = P4 = (A1 / A3)P S ×(A3 / A4)=(A1 / A4)P S Therefore, the initial and final state outputs F R is expressed as equations (19) and (20).

number

number

[0097] As an example, in the case of A2 / A1=A3 / A2=A4 / A3=2, F and F of a single-acting cylinder R This is the case where A4 = 2A3 = 4A2 = 8A1. The compressed air supply pressure is P S = 0.8MPa (abs). That is, P S =8P a It is.

[0098] The output F of the initial and final states during the outward stroke is as follows:

number

number

[0099] In a single-acting cylinder, only the power F on the forward stroke is important. Its power at the beginning of the forward stroke is greater than that of a single cylinder, but not twice as much, and at the end it is not much different from the single cylinder, because there is no compressed air supply on the return stroke.

[0100] 5. Optimization of cylinder pressure area (1) Description of design parameters Here, we consider the pressure-receiving area ratio of the cylinder. Therefore, we set the pressure-receiving area ratio as follows: A2 / A1=α A3 / A2=β A4 / A3=γ

[0101] As it is, there are three parameters, which makes it difficult to study. Therefore, we will proceed with the study with α = γ as a constraint. This is because α and γ are the area ratios of both sides of the same cylinder. Therefore, we have the following: A2 / A1=α A3 / A2=β A4 / A3=α

[0102] Furthermore, the compressed air supply pressure is P S = 0.8MPa (abs), and P S =8P a Therefore, in order to utilize all the force required to expand the compressed air to atmospheric pressure, the product of the area ratios was set to 8. That is, α 2 β=8 This imposes a constraint.

[0103] (2) Relationship between the output of a double-acting cylinder and the pressure-receiving area ratio The output F during the forward stroke is obtained by substituting the above design parameters into equations (12) and (13), and is expressed as follows:

number

[0104] Output F during the return stroke Ris obtained by substituting the above design parameters into equations (15) and (16), and is expressed as follows:

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[0105] 13 is a diagram showing the relationship between the output magnification and α of the double-acting double-cylinder actuator 100. During the forward stroke (x=L→0), the output changes from the line of F(x=L) toward the line of F(x=0). During the return stroke (x=0→L), the output F R is F R From the (x=0) line to F R It changes toward the line (x=L). The area where the average of both outputs during that period is greater than 2 is the area indicated by the thick arrow in the figure. When α = 2.06 and β = 1.89, F (mean) =(2.04)A1P S ,F R( mean) =(2.04)A1P S , In this case, output occurs during both the forward and return strokes. F ,F R The average value of the single cylinder power A1P S It is about twice as much.

[0106] (3) Relationship between the output of a single-acting cylinder and the pressure-receiving area ratio The output F during the forward stroke is obtained by substituting the above design parameters into equations (17) and (18), and is expressed as follows:

number

[0107] Output F during the return stroke R is obtained by substituting the above design parameters into equations (19) and (20), and is expressed as follows:

number

[0108] 14 is a diagram showing the relationship between the output magnification and α of the single-acting double-cylinder actuator 100. During the forward stroke (x=L→0), the output changes from the line of F(x=L) toward the line of F(x=0). During the return stroke (x=0→L), the output F R is F R From the (x=0) line to F R It changes toward the line (x=L). The area where the average output during the forward stroke is greater than 2 and is also relatively large in the latter half of the movement is the area indicated by the thick arrow in the figure. When α=1.51 and β=3.51, F (mean) =(2.0)A1P S ,F R(m ax) =(0.45)A1P S , In this case, the output during the outward stroke F The average value of F (mean) is the output of a single cylinder A1P S On the other hand, the power output during the return stroke is not needed, but it is possible to obtain nearly half the power output of a single cylinder.

[0109] 6. Smoothing the output of the double cylinder actuator 100 As described above, in the double cylinder actuator 100, as the displacement of the cylinder increases, the pressure inside the cylinder decreases, resulting in a smaller output. In applications where this is undesirable, a "negative spring characteristic" can be introduced to smooth the output.

[0110] FIG. 15 is a diagram showing a double cylinder actuator 100A with smoothed output. The double cylinder actuator 100A has magnets 170, 172 provided near the stroke end, i.e., near x=L and x=0. These magnets 170, 172 provide a characteristic similar to a negative spring characteristic. Specifically, the output decreases as the pistons 114, 134 approach the stroke end, but this decrease is compensated for by the attractive force of the magnets 170, 172. Also, at the start of the stroke, the cylinder outputs F, F Ris weakened by the attractive force of the magnet. In this way, the outputs F and F in the initial state and the final state R can be smoothed to some extent.

[0111] Note that the means for introducing the negative spring characteristic is not limited to using a magnet. For example, a method such as attaching a two-position stable spring to the piston can also be considered.

[0112] Note that in the case of a single-acting cylinder, the magnet 170 is not necessary and only the magnet 172 may be used.

[0113] As described above, the present disclosure has been described based on the embodiments. These embodiments are examples, and it is understood by those skilled in the art that various modifications are possible for each component and the combination of each processing process, and such modifications are also within the scope of the present disclosure. Hereinafter, such modifications will be described.

[0114] FIGS. 16(a) to (c) are diagrams showing the basic form and Modification Example 1 and Modification Example 2 of the double-cylinder actuator 100.

[0115] FIG. 16(a) shows the basic form of the double-cylinder actuator 100, which has the same configuration as FIG. 5, and the relationship A1 < A2 < A3 < A4 holds. Note that in FIG. 16(a), the right rod 122 of the first cylinder 110 and the left rod 140 of the second cylinder 130 have the same cross-sectional area.

[0116] In the basic form, the first cylinder 110 and the second cylinder 130 are both double-rod cylinders, but it is not limited thereto. In Modification Example 1 of FIG. 16(b), a single-rod cylinder with the right rod 142 omitted is used for the second cylinder 130. Also in this case, the relationship A1 < A2 < A3 < A4 is maintained.

[0117] Modification Example 2 of FIG. 16(c) is obtained by swapping the arrangements of the first cylinder 110 and the second cylinder 130.

[0118] Figs. 17(a) and (b) are diagrams showing Modification 3 and Modification 4 of the double-cylinder actuator 100. In Modification 3 of Fig. 17(a), in Fig. 16(a), the positions of the second air chamber 162 and the fourth air chamber 164 are interchanged. That is, the left air chamber 116 of the first cylinder 110 is assigned to the first air chamber 161, the right air chamber 118 of the first cylinder 110 is assigned to the fourth air chamber 164, the left air chamber 136 of the second cylinder 130 is assigned to the third air chamber 163, and the right air chamber 138 of the second cylinder 130 is assigned to the second air chamber 162. Here too, the relationship A1 < A2 < A3 < A4 holds.

[0119] Modification 4 of Fig. 17(b) is obtained by interchanging the first cylinder 110 and the second cylinder 130 of Fig. 17(a). In Figs. 16(c) and 17(a) and (b), the control valve 150a for the double-acting cylinder is shown, but it may be replaced with the control valve 150b for the single-acting cylinder.

[0120] The following techniques can be understood from Figs. 16(a) to (c) and Figs. 17(a) and (b). The double-cylinder actuator 100 includes a first cylinder 110 and a second cylinder 130, and their first piston 114 and second piston 134 are connected so that their displacement amounts are the same. The first piston 114 has two pressure-receiving surfaces, and the second piston 134 has two pressure-receiving surfaces, so that there are a total of four pressure-receiving surfaces. Among them, the pressure-receiving area of one side (the left side in the figure) of the first piston 114 is the smallest (A1), and the pressure-receiving area of the same side (the left side) of the second piston 134 is the third smallest (A3). When the two air chambers of the first cylinder 110 and the two air chambers of the second cylinder are called the first air chamber, the second air chamber, the third air chamber, and the fourth air chamber in order from the smallest to the largest pressure-receiving area, the control valve 150: (i) in the forward stroke, connects the air pressure source to the first air chamber, connects the second air chamber and the third air chamber, and opens the fourth air chamber to the atmosphere.

[0121] Figs. 18(a) and (b) are diagrams showing the double-cylinder actuator 100a according to Modification 5 and Modification 6. In the previous embodiments, the first cylinder 110 and the second cylinder 130 were arranged coaxially, but this is not the limit.

[0122] In the fifth modified example in Fig. 18(a), the first cylinder 110 and the second cylinder 130 of the double cylinder actuator 100 in Fig. 1 are arranged non-coaxially (parallel). For example, the first piston 114 and the second piston 134 are connected to each other at their right rods 122, 142 via a connecting member 180. The connecting member 180 may be the load 2 itself.

[0123] The sixth modification in Fig. 18(b) is obtained by omitting the right rods 122 and 142 of the fifth modification in Fig. 18(a). The first piston 114 and the second piston 134 are connected to the left rods 120 and 140 via a connecting member 180. The connecting member 180 may be the load 2 itself.

[0124] 19(a) and (b) are diagrams showing a double cylinder actuator 100 according to Modifications 7 and 8. Modification 7 in FIG. 19(a) is obtained by arranging the first cylinder 110 and the second cylinder 130 of Modification 3 in FIG. 16(c) non-coaxially (parallel). The first piston 114 and the second piston 134 are connected to the right rods 122, 142 via a connecting member 180. The connecting member 180 may be the load 2 itself.

[0125] The eighth modified example in Fig. 19(b) is a modification of the seventh modified example in Fig. 19(a) such that the first piston 114 and the second piston 134 are connected to the left rods 120, 140 via a connecting member 180. Furthermore, in this eighth modified example, the right rod 122 is omitted.

[0126] Although the control valve 150a for a double-acting cylinder is shown in Figures 18(a), (b) and Figures 19(a), (b), it may be replaced with a control valve 150b for a single-acting cylinder.

[0127] Generally, single rod cylinders are less expensive than double rod cylinders. Figures 20(a) and (b) show a double cylinder actuator 100a using a single rod cylinder. Figure 20(a) is a left-right inversion of the double cylinder actuator 100a in Figure 18(b), and acts on the load on the right side of the page. This double cylinder actuator 100a pulls the load in the forward stroke and pushes the load in the return stroke. Figure 20(b) shows a different way of extracting force, pushing the load in the forward stroke and pulling the load in the return stroke, the opposite of Figure 20(a). Although Figures 20(a) and (b) show a control valve 150a for a double acting cylinder, it may be replaced with a control valve 150b for a single acting cylinder.

[0128] FIG. 21 is a diagram showing a double cylinder actuator 100a according to the ninth modification. This double cylinder actuator 100a is a double-acting actuator in which the configuration of the control valve 150a is changed based on the double cylinder actuator 100a of FIG. 20(b). In FIG. 21, the control valve 150a includes a first control valve 152 and a second control valve 154. The first control valve 152 and the second control valve 154 are each a four-port two-position valve (four-port two-position directional control valve). In the first state (first position), the first port (1) of the control valves 152 and 154 is connected to the second port (2), and the third port (3) and the fourth port (4) are closed. In the second state (second position), the first port (1) and the second port (2) of the control valves 152 and 154 are closed, and the fourth port (4) is connected to the third port (3).

[0129] The first port (1) and the third port (3) of the first control valve 152 are connected to the second air chamber 162. The second port (2) of the first control valve 152 is connected to the third air chamber 163 and the fourth port (4) of the second control valve 154. The fourth port (4) of the first control valve 152 is connected to the first air chamber 161 and the air pressure source 102. The first port (1) and the third port (3) of the second control valve 154 are connected to the fourth air chamber 164. The second port (2) of the second control valve 154 is connected to the atmosphere 104.

[0130] In Figure 21, the first control valve 152 and the second control valve 154 are in the first position, which realizes the forward stroke. The return stroke is realized by switching the first control valve 152 and the second control valve 154 to the second position. Since a 4-port 2-position directional control valve, or a 4-port 3-position directional control valve with a closed center function added thereto, is a general-purpose part, the double cylinder actuator 100a in Figure 21 can be realized at low cost using commercially available products.

[0131] Fig. 22 is a diagram showing a double cylinder actuator 100a according to Modification 10. This double cylinder actuator 100a is obtained by dividing the first control valve 152 in Fig. 21 into two 2-port 2-position directional control valves 152_1, 152_2, and dividing the second control valve 154 in Fig. 21 into two 2-port 2-position directional control valves 154_1, 154_2. Since the 2-port 2-position directional control valves are general-purpose parts, they can be realized at low cost by using commercially available products.

[0132] FIG. 23 is a diagram showing a double cylinder actuator 100b according to Modification 11. This double cylinder actuator 100b is a single-acting version of the double cylinder actuator 100a in FIG. 21. The control valve 150b includes a first control valve 155 and a second control valve 154. The second control valve 154 has the same configuration as the second control valve 154 in FIG. 21. The first control valve 155 is a 4-port 2-position directional control valve, in which the first port (1) is connected to the second air chamber 162, the second port (2) is connected to the third air chamber 163, the third port (3) is connected to the first air chamber 161, and the fourth port (4) is connected to the air pressure source 102.

[0133] In the first state (first position), the first control valve 155 is conductive from the first port (1) to the second port (2) and is conductive from the fourth port (4) to the third port (3). In the second state (second position), the first control valve 155 is conductive (open state) between the first port (1) and the third port (3) and is closed state (closed) between the second port (2) and the fourth port (4).

[0134] 23, the first control valve 155 and the second control valve 154 are in the first position, which allows the forward stroke to be realized. The first control valve 155 and the second control valve 154 are switched to the second position to allow the return stroke to be realized. The second control valve 154 can be a general-purpose product.

[0135] Following the modification of FIG. 22, the four-port directional control valve of FIG. 23 may be divided into two-port directional control valves.

[0136] In addition to those shown here, there are many variations in the configuration of the control valves 150a, 150b and such variations are within the scope of the present disclosure.

[0137] (Other variations) In the embodiment, the double cylinder actuator 100 is configured by a combination of two cylinders with rods, but this is not limited thereto.

[0138] For example, a double cylinder actuator 100 may be constructed by combining two guided cylinders.

[0139] Alternatively, two rodless cylinders can be combined to form the double cylinder actuator 100. Rodless cylinders come in two types: slit type and magnet type. When using the slit type, the pressure-receiving area can be changed like a rod according to the cross-sectional area of ​​the cushion pipe by extending the cushion pipe from the center of the cylinder head to the piston. Even when using the magnet type, the pressure-receiving area can be controlled according to the cross-sectional area of ​​the rod by adding a rod inside.

[0140] In this way, the configuration of the cylinders that make up the double cylinder actuator 100 is not particularly limited, and the actuator can be configured by combining various cylinders having pistons with different pressure-receiving areas in the two air chambers.

[0141] In the embodiment, a double-cylinder actuator 100 having two cylinders has been described, but the number of cylinders may be increased to three, four, etc., and will be generally referred to as a multi-cylinder actuator. A multi-cylinder actuator has the following characteristics.

[0142] The multi-cylinder actuator includes a plurality of N (N≧2) cylinders and a control valve. Each of the N cylinders includes a cylinder tube and a piston that divides the space in the cylinder tube into two air chambers. The pistons of the N cylinders are connected so that they have the same displacement. One of the pressure-receiving areas of the i-th (1≦i≦N) piston is the (2i-1)th smallest. When the two air chambers of each of the N cylinders (a total of 2N air chambers) are referred to in order from the smallest to the largest pressure-receiving areas as the first air chamber, the second air chamber, ..., the (2N-1)th air chamber, and the (2N)th air chamber, the control valve connects an air pressure source to the first air chamber in the (i) forward stroke, opens the (2N) air chamber to the atmosphere, and connects the other pairs of adjacent two air chambers.

[0143] In a double-acting multi-cylinder actuator, the control valve (ii) on the return stroke connects the first and second air chambers to an air pressure source, and for the third to (2N)th air chambers, connects pairs of two adjacent air chambers.

[0144] In the single-acting multi-cylinder actuator, the control valve (iii) connects adjacent pairs of air chambers for the first air chamber to the (2N)th air chamber during the return stroke.

[0145] The present disclosure has been described using specific terms based on the embodiments, but the embodiments merely illustrate the principles and applications of the present disclosure, and many modifications and changes in arrangement are permitted to the embodiments without departing from the spirit of the present invention defined in the claims. [Industrial Applicability]

[0146] The present disclosure can be used in pneumatic actuators. [Explanation of symbols]

[0147] 10 Pneumatic cylinder 12 Piston 14 Left ventricle 16 Right ventricle 34 Left oil chamber 36 Right oil chamber 100 Double Cylinder Actuator 102 Air pressure source 104 Atmosphere 110 First cylinder 112 First cylinder tube 114 First piston 116 Left air chamber 118 Right Air Chamber 120 Left Rod 122 Right Rod 130 No. 2 cylinder 132 Second cylinder tube 134 Second piston 136 Left Air Chamber 138 Right Air Chamber 140 Left Rod 142 Right Rod 150 Control valve 152 First control valve 154 Second control valve 161 First Air Chamber 162 Second Air Chamber 163 Third Air Chamber 164 4th Air Chamber

Claims

1. a first cylinder including a first cylinder tube and a first piston that divides a space within the first cylinder tube into two air chambers; a second cylinder including a second cylinder tube and a second piston that divides a space in the second cylinder tube into two air chambers and is connected to the first piston so as to have the same displacement amount; A control valve; Equipped with Among the two pressure receiving surfaces of the first piston and the two pressure receiving surfaces of the second piston, one pressure receiving area of ​​the first piston is the smallest, and the pressure receiving area of ​​the same side of the second piston is the third smallest, When the two air chambers of the first cylinder and the two air chambers of the second cylinder are referred to as a first air chamber, a second air chamber, a third air chamber and a fourth air chamber in order from the one with the smallest pressure-receiving area to the one with the largest pressure-receiving area, the control valve is characterized in that (i) during a forward stroke, only the first air chamber is connected to an air pressure source, the second air chamber is connected to only the third air chamber, and only the fourth air chamber is open to the atmosphere.

2. 2. The pneumatic actuator according to claim 1, wherein the control valve (ii) during a return stroke, connects only the first air chamber and the second air chamber to the air pressure source, and connects the third air chamber to only the fourth air chamber.

3. 2. The pneumatic actuator according to claim 1, wherein the control valve (iii) during a return stroke, is in a state in which only the first air chamber is connected to the second air chamber while being disconnected from the air pressure source, and the third air chamber is connected to only the fourth air chamber.

4. 4. The pneumatic actuator according to claim 1, wherein the first cylinder and the second cylinder are arranged non-coaxially.

5. 5. The pneumatic actuator according to claim 4, wherein the first air chamber and the second air chamber are formed in the same cylinder, and the third air chamber and the fourth air chamber are formed in the same cylinder.

6. 6. The pneumatic actuator according to claim 5, wherein the first cylinder and the second cylinder are single rod cylinders.

7. 4. The pneumatic actuator according to claim 1, wherein the first cylinder and the second cylinder are arranged coaxially.

8. The control valve includes a first control valve and a second control valve each having four ports; the first control valve and the second control valve are configured such that (a) in a first position, electrical communication occurs from a first port to a second port, and a third port and a fourth port are in a closed state, and (b) in a second position, the first port and the second port are in a closed state, and electrical communication occurs from the fourth port to the third port; 4. The pneumatic actuator according to any one of claims 1 to 3, characterized in that the first port and the third port of the first control valve are connected to the second air chamber, the second port of the first control valve is connected to the third air chamber and the fourth port of the second control valve, the fourth port of the first control valve is connected to the first air chamber and the air pressure source, the first port and the third port of the second control valve are connected to the fourth air chamber, and the second port of the second control valve is connected to the atmosphere.

9. A plurality of N (N≧2) cylinders, each of which includes a cylinder tube and a piston that divides a space within the cylinder tube into two air chambers; A control valve; Equipped with The pistons of the N cylinders are connected so as to have equal displacements, Among all the pressure receiving surfaces of the pistons of the N cylinders, the pressure receiving area of ​​one side of the i-th (1≦i≦N) piston is the (2i−1)th smallest, When the two air chambers of each of the N cylinders are referred to in order from the one with the smallest pressure-receiving area to the one with the largest pressure-receiving area as the first air chamber, the second air chamber, ..., the (2N-1)th air chamber, and the (2N)th air chamber, the control valve is, (i) on a forward stroke, in a state where only the first air chamber is connected to an air pressure source and only the (2N) air chamber is opened to the atmosphere, and where j = 1, 2, ..., N-1, the (2j)th air chamber is connected only to the (2j+1)th air chamber.

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